The present invention relates generally to remote testing of energized, high voltage utility transformers and, more specifically, to an assembly tool and procedure for remotely penetrating a utility transformer, extracting oil therefrom for analysis, and resealing the transformer.
In recent years the presence of PCB's used in high voltage utility transformers has been of concern. When PCB's are discovered in the cooling oil of the transformer, the transformer is replaced. With the large number of utility transformers in service, problems in testing has become an issue as much as the actual detection and removal of PCB-contaminated units.
Prior to this invention, before utility transformers were tested, power to the transformer was interrupted. After interrupting power to a transformer, a hole was typically drilled near the base of the transformer, and a small amount of oil was drained out. The hole was then closed with a plug. Typically, the plug was effective only for a limited period of time; normal vibrations such as from 60-cycle a.c. electrical power and from passing motor vehicles would cause the plug to loosen and leak, causing a major environmental and cost concern of utility companies.
Deenergizing the transformer by interrupting power to a power grid causes customer dissatisfaction and risks liability for failures caused in facilities that were not sufficiently notified or given adequate time to prepare. With a growing number of facilities dependent on computer processors and other similar equipment, maintaining continuous power is a high priority. It is therefore much preferred to have a oil-sampling system that does not require power interruption to the transformer. However, industry rules require that operators remain at least 24 inches from any energized high voltage utility transformer to minimize danger to the operator. Any tool used by an operator inside that protective distance must provide for electrical insulation of the operator from the tool. Therefore, any procedure for sampling oil from an energized utility transformer must employ a electrically insulating tool or tool system that can be operated at 24 inches from the transformer.
It is therefore an object of the present invention to provide a tool and procedure for facilitating the extraction of oil samples from energized utility transformers.
Another object of the invention is to provide a tool that enables a workman to safely extract oil from an energized transformer by operating the tool a safe distance from the transformer.
Still another object of the invention restore the long-term integrity of the utility transformer after oil is extracted.
A final object is to extract transformer oil without potentially introducing a costly maintenance and environmental problem.
The above objects are attained in the present invention in a hot-stick utility transformer combination selective tool for remote use by an operator for penetrating a utility transformer above the oil line within the transformer, extracting an oil sample with a syringe element, and closing and resealing the transformer.